1. Technical Field
The present invention relates to technology for representing a gray scale by applying either an ON voltage or an OFF voltage to each pixel in each of a plurality of subfields within a field.
2. Related Art
Typically, subfield driving in which either an ON voltage or an OFF voltage is selectively applied to an electro-optical element (for example, a liquid crystal element) in each of a plurality of subfields, which is acquired by dividing a field, has been proposed (for example, Japanese Patent No. 3918536). In the subfield driving, a gray scale is represented by changing the ratio of a time during which the ON voltage is applied to the electro-optical element to a total time of a field in accordance with a designated gray scale.
However, there are cases where the behavior of the electro-optical element depends on the temperature. FIG. 13 is a graph showing a change in the gray scale of the electro-optical element (liquid crystal element) over time for a plurality of cases where the temperatures are different from one another. In FIG. 13, a change in the transmittance is exemplified in the case where the ON voltage is applied to a liquid crystal element of the normally-white mode, in which the transmittance becomes the minimum (black display) at the time of application of the ON voltage, from a time point t1 and the OFF voltage is applied to the liquid crystal element from a time point t2.
The viscosity of the liquid crystal increases as the temperature is lowered. Thus, as can be noticed from FIG. 13, as the temperature of the liquid crystal element is lower, the speed at which the transmittance is increased after the OFF voltage is applied (after elapse of the time point t2) is decreased. Accordingly, there is a problem in that the gray scale actually perceived by an observer changes in accordance with the temperature of the liquid crystal element (in particular, the gray scale becomes higher as the temperature of the liquid crystal element is higher) even in the case where the time interval during which the ON voltage is applied is the same.